279 research outputs found

    In-flight flow visualization with pressure measurements at low speeds on the NASA F-18 high alpha research vehicle

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    In-flight results from surface and off-surface flow visualizations and from extensive pressure distributions document the vortical flow on the leading edge extensions (LEX) and forebody of the NASA F-18 high alpha research vehicle for low speeds and angles of attack up to 50 degs. Surface flow visualization data, obtained using the emitted fluid technique, were used to define separation lines and laminar separation bubbles. Off-surface flow visualization data, obtained by smoke injection, were used to document both the path of the vortex cores and the location of vortex core breakdown. The location of vortex core breakdown correlated well with the loss of suction pressure on the LEX and with the flow visualization results from ground facilities. Surface flow separation lines on the LEX and forebody corresponded well with the end of pressure recovery under the vortical flows. Correlation of the pressures with wind tunnel results show fair to good correlation

    Summary of in-flight flow visualization obtained from the NASA high alpha research vehicle

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    A summary of the surface and off-surface flow visualization results obtained in flight on the F-18 high alpha research vehicle (HARV) is presented, highlighting the extensive 3-D vortical flow on the aircraft at angles of attack up to 50 degs. The emitted fluid technique, as well as tufts and flow cones, were used to document the surface flow. A smoke generator system injected smoke into the vortex cores generated by the forebody and leading edge extensions (LEXs). Documentation was provided by onboard still and video, by air-to-air, and by postflight photography. The surface flow visualization techniques revealed laminar separation bubbles near the forebody apex, lines of separation on the forebody and LEX, and regions of attached and separated flow on the wings and fins. The off-surface flow visualization techniques showed the path of the vortex cores on the forebody and LEX as well as the LEX vortex core breakdown location. An interaction between the forebody and LEX vortices was noted. The flow over the surfaces of the vertical tail was categorized into regions of attached, unsteady, or separated flow using flow tufts

    Connection Between Gradient and Slope

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    Students will consider how gradient (slope) affects the velocity of an object rolling down an incline

    Inferior alveolar and lingual nerve injuries: An overview of diagnosis and management

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    Oral and maxillofacial surgery operations are susceptible to cause injury to terminal branches of the trigeminal nerve. The mandibular division is more prone to injury than ophthalmic and maxillary nerves. Inferior alveolar branch of the trigeminal nerve is the most commonly injured branch, followed by the lingual nerve. These nerves may be subjected to neurosensorial disturbance during third molar surgery, followed by sagittal split ramus osteotomy, endodontic therapy and dental implant placement. Local anesthetic injections, pre-prosthetic surgery, various other types of orthognathic surgery, ablative tumor surgery involving mandibular resections, osteoradionecrosis, osteomyelitis or maxillofacial trauma are among other potential etiologic factors. If an inferior alveolar or lingual nerve injury occurs, a timely diagnosis and a proper management are key factors to avoid further or permanent damage. A wide range of therapeutic modalities are available in managing nerve injuries, ranging from simple observation to complex grafting, depending on various factors. Data regarding nerve injuries may not always be reliable since most are based upon personal experience and in a retrospective nature. It is also challenging to draw proper conclusions from studies on nerve injuries due to the differences in outcome criteria and assessment methods. Still, an accurate knowledge of anatomy should be combined with both clinical and radiological data to avoid any nerve-related complications. Thus, this article will present a narrative review of the current literature on the inferior alveolar and lingual nerve injuries, focusing on the functional assessment methods, factors influencing recovery, the contemporary management protocols as well as future trends in nerve repairs

    Long-Term High-Temperature Stability of Functionalized Graphene Oxide Nanoplatelets in Arab-D and API Brine

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    Partially reduced graphene oxide (prGO) was covalently functionalized with a zwitterionic polymer polyzwitterionic polymer to afford a composite material with excellent dispersibility and long-term stability in high salinity brines including standard API and Arab-D found in deep oil reservoirs. When heated at 90 °C, the dispersions remained stable in excess of 140 days. These results suggest the utility of imidazolium-based polymers for brine stabilization as well as the use of diazonium containing polymers for a “grafting-to” approach to nanocarbon functionalization.Saudi Aramco (MIT Energy Initiative)Massachusetts Institute of Technology. Institute for Soldier NanotechnologiesCamille & Henry Dreyfus Foundation. Postdoctoral Program in Environmental Chemistry (Fellowship

    Cyborg beast: a low-cost 3d-printed prosthetic hand for children with upper-limb differences

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    Background There is an increasing number of children with traumatic and congenital hand amputations or reductions. Children\u27s prosthetic needs are complex due to their small size, constant growth, and psychosocial development. Families’ financial resources play a crucial role in the prescription of prostheses for their children, especially when private insurance and public funding are insufficient. Electric-powered (i.e., myoelectric) and body-powered (i.e., mechanical) devices have been developed to accommodate children’s needs, but the cost of maintenance and replacement represents an obstacle for many families. Due to the complexity and high cost of these prosthetic hands, they are not accessible to children from low-income, uninsured families or to children from developing countries. Advancements in computer-aided design (CAD) programs, additive manufacturing, and image editing software offer the possibility of designing, printing, and fitting prosthetic hands devices at a distance and at very low cost. The purpose of this preliminary investigation was to describe a low-cost three-dimensional (3D)-printed prosthetic hand for children with upper-limb reductions and to propose a prosthesis fitting methodology that can be performed at a distance. Results No significant mean differences were found between the anthropometric and range of motion measurements taken directly from the upper limbs of subjects versus those extracted from photographs. The Bland and Altman plots show no major bias and narrow limits of agreements for lengths and widths and small bias and wider limits of agreements for the range of motion measurements. The main finding of the survey was that our prosthetic device may have a significant potential to positively impact quality of life and daily usage, and can be incorporated in several activities at home and in school. Conclusions This investigation describes a low-cost 3D-printed prosthetic hand for children and proposes a distance fitting procedure. The Cyborg Beast prosthetic hand and the proposed distance-fitting procedures may represent a possible low-cost alternative for children in developing countries and those who have limited access to health care providers. Further studies should examine the functionality, validity, durability, benefits, and rejection rate of this type of low-cost 3D-printed prosthetic device

    Building an Economical and Sustainable Lunar Infrastructure to Enable Lunar Industrialization

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    A new concept study was initiated to examine the architecture needed to gradually develop an economical, evolvable and sustainable lunar infrastructure using a public/private partnerships approach. This approach would establish partnership agreements between NASA and industry teams to develop a lunar infrastructure system that would be mutually beneficial. This approach would also require NASA and its industry partners to share costs in the development phase and then transfer operation of these infrastructure services back to its industry owners in the execution phase. These infrastructure services may include but are not limited to the following: lunar cargo transportation, power stations, communication towers and satellites, autonomous rover operations, landing pads and resource extraction operations. The public/private partnerships approach used in this study leveraged best practices from NASA's Commercial Orbital Transportation Services (COTS) program which introduced an innovative and economical approach for partnering with industry to develop commercial cargo services to the International Space Station. This program was planned together with the ISS Commercial Resupply Services (CRS) contracts which was responsible for initiating commercial cargo delivery services to the ISS for the first time. The public/private partnerships approach undertaken in the COTS program proved to be very successful in dramatically reducing development costs for these ISS cargo delivery services as well as substantially reducing operational costs. To continue on this successful path towards installing economical infrastructure services for LEO and beyond, this new study, named Lunar COTS (Commercial Operations and Transport Services), was conducted to examine extending the NASA COTS model to cis-lunar space and the lunar surface. The goals of the Lunar COTS concept are to: 1) develop and demonstrate affordable and commercial cis-lunar and surface capabilities, such as lunar cargo delivery and surface power generation, in partnership with industry; 2) incentivize industry to establish economical and sustainable lunar infrastructure services to support NASA missions and initiate lunar commerce; and 3) encourage creation of new space markets for economic growth and benefit. A phased-development approach was also studied to allow for incremental development and demonstration of capabilities needed to build a lunar infrastructure. This paper will describe the Lunar COTS concept goals, objectives and approach for building an economical and sustainable lunar infrastructure. It will also describe the technical challenges and advantages of developing and operating each infrastructure element. It will also describe the potential benefits and progress that can be accomplished in the initial phase of this Lunar COTS approach. Finally, the paper will also look forward to the potential of a robust lunar industrialization environment and its potential effect on the next 50 years of space exploration

    Recursive simulation of quantum annealing

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    The evaluation of the performance of adiabatic annealers is hindered by lack of efficient algorithms for simulating their behaviour. We exploit the analyticity of the standard model for the adiabatic quantum process to develop an efficient recursive method for its numerical simulation in case of both unitary and non-unitary evolution. Numerical simulations show distinctly different distributions for the most important figure of merit of adiabatic quantum computing - the success probability - in these two cases

    Qualitative Descriptors Used by Patients Following Orthognathic Surgery to Portray Altered Sensation

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    Following orthognathic surgery, patients use qualitatively different words to describe the altered sensation on their face that results from tissue inflammation and nerve injury. These words indicate normal, hypoesthetic, paresthetic, and dysesthetic sensations, and reflect the intrusiveness of the alteration. Our intent was to study the words chosen by patients from a standardized list to characterize sensory recovery during the first 6 months after surgery and to examine whether patients who underwent different surgical procedures tended to choose different sets of words
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